Increased Lifetime Risk of ESRD in Familial IgA Nephropathy

Chronic Tonsillitis and IgA Nephropathy: Findings From a Nationwide Japanese Cohort Study

RATIONALE & OBJECTIVE

Little is known regarding the association between chronic tonsillitis and the onset of IgA nephropathy (IgAN). In the present study, we examined the potential relationship between chronic tonsillitis and a subsequent risk of developing IgAN.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

4,311,393 individuals without a history of IgAN identified between January 2005 and May 2022 within a Japanese nationwide epidemiological database, the JMDC Claims Database, representing health claims to over 60 insurers.

EXPOSURE

Comorbid chronic tonsillitis based on diagnosis codes.

OUTCOME

IgAN occurrence.

ANALYTICAL APPROACH

Cause-specific Cox proportional hazards analysis adjusting for potential confounding factors was employed to estimate hazard ratios (HRs).

RESULTS

Comorbid chronic tonsillitis was identified in 12,842 individuals, constituting 0.3% of the cohort. The cohort had a median age of 44 years (IQR, 36-53), and males accounted for 57.9%, with a follow-up of 1,089 days (IQR, 532-1,797), during which 2,653 cases of IgAN developed. Cumulative incidence curve showed a higher cumulative incidence of IgAN in individuals with chronic tonsillitis compared with their counterparts without this condition. Multivariable cause-specific analysis further demonstrated that individuals with chronic tonsillitis had an elevated risk of developing IgAN, with HR of 2.72 (95% CI, 1.79-4.14).

LIMITATIONS

Potential residual confounders, and lack of consideration for ethnic distinctions.

CONCLUSIONS

Using a large-scale epidemiological dataset, these findings suggest a relationship between chronic tonsillitis and an elevated risk of IgAN development in the general Japanese population.

PLAIN-LANGUAGE SUMMARY

IgA nephropathy (IgAN), the most prevalent form of primary glomerulonephritis worldwide, is associated with unfavorable long-term kidney survival and life expectancy. Despite the substantial implications, the early detection of IgAN still remains challenging due to its commonly asymptomatic clinical presentation. Consequently, the exploration of risk factors assumes a critical research priority. Prior studies have reported the potential role of tonsilitis in the pathogenesis of IgAN. In this study, we assessed whether chronic tonsillitis was associated with the subsequent development of IgAN using a nationwide epidemiological dataset incorporating over 4,000,000 individuals. Within this large-scale cohort, our findings revealed an association between a history of tonsillitis and a greater risk of developing IgAN. These findings should heighten awareness of the potential susceptibility of people with chronic tonsilitis to IgAN.

Genetics of IgA nephrology: risks, mechanisms, and therapeutic targets

IgA nephropathy (IgAN) is a genetically complex multifactorial trait. Over the past decade, population-based genome-wide association studies (GWAS) have identified more than 30 IgAN risk loci, providing novel perspectives on both the epidemiology of the disease and its underlying molecular mechanisms. In addition, the association between IgAN and galactose-deficient IgA1 (Gd-IgA1) presented another avenue for genetic exploration due to the heritability of the elevated serum Gd-IgA1 levels. These endeavors also yielded and enabled refinement of polygenic risk scores, which may help identify specific groups of individuals at significantly increased risks, leading to stratifications of medical treatments. In this review, we aim to explore the existing evidence for genetic causation in IgAN. We summarize the state of genetic research in IgAN and how it has led to the reformulation of the new pathogenesis model and novel therapeutic targets.

Nutritional intervention in end-stage renal disease: a clinical trial study

Objective

Chronic kidney disease is a global health problem, and end-stage renal disease (ESRD) has a major impact on patients' quality of life and prognoses. However, studies on individualized nutritional therapy for patients with ESRD need more complementary evidence.

Methods

A clinical study was conducted based on a small population. It included patients with ESRD who underwent dialysis treatment in the Taicang Hospital Department of Nephrology, Soochow University, China, between January 2019 and December 2021. According to the randomized number table method, patients were divided into the nutritional treatment group (NIG) and the non-nutritional intervention control group (NNIG). There were 84 patients in the NIG and 92 patients in the NNIG. This study analyzed the changes in residual renal function (RRF) and indicators of blood and kidney function in ESRD with personalized nutritional therapy.

Results

The results show that nutritional interventions for ESRD are effective in reducing the rate of decline in RRF and improving indicators of blood and kidney function in patients with ESRD. It was also found that patients with diabetes mellitus gained fewer health benefits per unit of RRF improvement with individualized nutritional therapy.

Conclusion

This study provides important information about the treatment effects and factors associated with individual nutritional interventions in a population with ESRD. These results contribute to a better understanding of the effects of nutritional therapy in ESRD and provide a basis for managing it. Further studies should focus on specific populations and potential interventions to improve patient prognosis.

Uromodulin and progression of IgA nephropathy

Background

This study investigates the link between genetic variants associated with kidney function and immunoglobulin A (IgA) nephropathy (IgAN) progression.

Methods

We recruited 961 biopsy-proven IgAN patients and 651 non-IgAN end-stage renal disease (ESRD) patients from Ruijin Hospital. Clinical and renal pathological data were collected. The primary outcome was the time to ESRD. A healthy population was defined as estimated glomerular filtration rate >60 mL/min/1.73 m2 without albuminuria or hematuria. Fifteen single-nucleotide polymorphisms (SNPs) were selected from a genome-wide association study of kidney function and genotyped by the SNaPshot. Immunohistochemistry in renal tissue and ELISA in urine samples were performed to explore the potential functions of genetic variations.

Results

The rs77924615-G was independently associated with an increased risk for ESRD in IgAN patients after adjustments for clinical and pathologic indices, and treatment (adjusted hazard ratio 2.10; 95% confidence interval 1.14-3.88). No significant differences in ESRD-free survival time were found among different genotypes in non-IgAN ESRD patients (log-rank, P = .480). Moreover, rs77924615 exhibited allele-specific enhancer activity by dual-luciferase reporter assay. Accordingly, the urinary uromodulin-creatinine ratio (uUCR) was significantly higher in healthy individuals with rs77924615 AG or GG than in individuals with AA. Furthermore, uromodulin expression in tubular epithelial cells was higher in patients with rs77924615 AG or GG. Finally, we confirmed that an increased uUCR (P = .009) was associated with faster IgAN progression.

Conclusion

The SNP rs77924615, which modulates the enhancer activity of the UMOD gene, is associated with renal function deterioration in IgAN patients by increasing uromodulin levels in both the renal tubular epithelium and urine.

Case Report: A Pathogenic Missense Variant of WT1 Cosegregates With Proteinuria in a Six-Generation Chinese Family With IgA Nephropathy

Immunoglobulin A (IgA) nephropathy (IgAN) is the most common type of primary glomerulonephritis worldwide. In addition to hematuria, proteinuria is observed in a considerable proportion of patients with IgAN and has proven to be a strong risk factor for disease progression. Although the exact pathogenesis of IgAN is still unclear, genetic factors are widely considered to play a role in its occurrence and development. Here, we investigated a large IgAN-associated pedigree of 47 members belonging to six generations. Two members of the family who presented with proteinuria and hematuria were diagnosed with IgAN through renal biopsy. Four other members also exhibited proteinuria or hematuria but without renal biopsy. Using whole-exome sequencing, we identified a likely pathogenic variant in WT1 (c.1397C>T; p.Ser466Phe) that cosegregated with proteinuria in the affected family members. In addition, another pathogenic variant in NPHS1 (c.3478C>T; p.Arg1160Ter) was identified; however, it did not cosegregate with abnormal proteinuria. Compared to individuals in the pedigree with only one heterozygous WT1 variant (c.1397C>T; p.Ser466Phe), the proband and her younger brother carried an additional WT1 variant (c.1433-10G>A) and presented with a more severe phenotype and rapid progression to end-stage kidney disease. Our findings suggest the WT1 missense variant (c.1397C>T; p.Ser466Phe)-induced primary podocyte injury might contribute to the proteinuria phenotype and IgAN progression in this pedigree.

Association of Immune and Inflammatory Gene Polymorphism With the Risk of IgA Nephropathy: A Systematic Review and Meta-Analysis of 45 Studies

IgA nephropathy is the most prevalent primary glomerulonephritis worldwide, with identical immunopathological characteristics caused by multiple etiologies as well as influenced by geographical and ethnical factors. To elucidate the role of immunologic and inflammatory mechanisms in the susceptibility to IgA nephropathy, we explored single nucleotide polymorphisms of related molecules in the immune pathways. We searched the PubMed database for studies that involved all gene variants of molecules in the 20 immunologic and inflammatory pathways selected from the Kyoto Encyclopedia of Genes and Genomes database. The odds ratios with their corresponding 95% confidence intervals in six genetic models (allele model, dominant model, homozygote model, heterozygote model, overdominant model, and recessive model) were summarized using fixed or random effect models. Subgroup analysis was conducted based on different ethnicities with generalized odds ratios. Heterogeneity was evaluated using the Q and I² tests. Begg’s funnel plot and Egger’s linear regression test were used to evaluating possible publication bias among the included studies, and sensitivity analysis was used to test the stability of the overall results. A total of 45 studies met our selection criteria and eight related genetic association studies were retrieved, including 320 single-nucleotide polymorphisms from 20 candidate pathways, ranging from 2000 to 2021. A total of 28,994 healthy people versus 20,600 IgA nephropathy patients were enrolled. Upon meta-analyzed results that TGFB1 (rs1800469, rs1982073, rs1800471), IL-1B (rs1143627), IL-18 (rs1946518), and TLR1 (rs5743557) showed effect with or without ethnicity difference. And 10 variants presented stable and robust related to IgA nephropathy. This research showed that genetic variants are related to the immunologic and inflammatory effects of IgA nephropathy pathogenesis. The meta-analysis results supported the previous researches, and may help deepen the understanding of pathogenesis and explore new targets for IgA nephropathy-specific immunotherapy.

Positive renal familial history in IgA nephropathy is associated with worse renal outcomes: a single-center longitudinal study

Background

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Although most IgAN cases are sporadic, few show a familial aggregation. However, the prevalence and prognosis of IgAN individuals with positive familial history (FH) of renal disorders remains uncertain. To address these issues, we conducted a longitudinal observational study on a single-institution cohort of patients with biopsy-proven IgAN.

Methods

A total of 467 IgAN patients who underwent renal biopsy during 1994 to 2019 were ascertained to have positive- or negative-FH by history taking and were followed for an average of 8.9 years. We compared the clinical and pathological features of the two subgroups. The primary outcome, a composite of a hard endpoint (end-stage renal disease [ESRD]) and surrogate endpoint (a 50% or more reduction in the estimated glomerular filtration rate [eGFR] from baseline), was evaluated. To estimate the risk for progression to ESRD, a Cox proportional hazards analysis was performed for a subset of patients who underwent follow-up for > 2 years and had an eGFR > 30 mL/min/1.73 m² at baseline (n = 389; observation, 8.7 years).

Results

Positive-FH subtype accounted for 11.6% (n = 54) of all IgAN patients. At baseline, there were no significant differences between the positive- and negative-FH subgroups regarding age, sex, comorbid disease, MEST-C score, observation period, and therapeutic interventions. However, the eGFR value at baselines was significantly lower in the positive-FH subgroup than in the negative-FH subgroup (P < 0.01). On multivariate analysis, positive-FH emerged an independent determinant of poorer renal outcomes (odds ratio, 2.31; 95% confidence interval, 1.10–4.85; P = 0.03), after adjusting for confounding factors. eGFR at follow-up was significantly lower in the positive-FH subgroup than in the negative-FH subgroup after adjustment for age and observation period.

Conclusions

Positive-FH was found in 11.6% of all IgAN patients, consistent with the incidence seen in previous literature. A significantly lower eGFR at baseline and last follow-up and unfavorable renal outcomes in the positive-FH subgroup suggest that certain genetic risk factors predisposing to renal failure may exist in a fraction of our IgAN cohort. (331 words).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02425-8.